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6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 3.1 Definitions | For the purposes of the present document, the following terms and definitions apply: active channel: any channel which has been assigned to a cable modem's transmit channel set either in a registration response message or a dynamic bonding request message, and prior to registration NOTE: After registration, the set of ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 3.2 Symbols | For the purposes of the present document, the following symbols apply: η Eta (lower case); a measure of modulation µ Mu/micron (lower case); represents 10-6 τ Tau (lower case); a measure of time µs Microsecond ETSI ETSI TS 103 311-2 V1.1.1 (2017-02) 27 |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 3.3 Abbreviations | For the purposes of the present document, the following abbreviations apply: ADC Analog-to-Digital Converter ANSI American National Standards Institute AWGN Additive White Gaussian Noise BCH Bose, Ray-Chaudhuri, Hocquenghem [codes] BER Bit Error Ratio BER Bit Error Rate BPSK Binary Phase Shift Keying BW BandWidth Cable... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 4 Requirements and Conventions | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 4.1 Requirements | Throughout the present document, the words that are used to define the significance of particular requirements are capitalized. These words are: "SHALL" This word means that the item is an absolute requirement of the present document. "SHALL NOT" This phrase means that the item is an absolute prohibition of the present... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 4.2 Conventions | In the present document, the following convention applies any time a bit field is displayed in a figure. The bit field should be interpreted by reading the figure from left to right, then top to bottom, with the most-significant bit (MSB) being the first bit read, and the least-significant bit (LSB) being the last bit ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5 Overview and Functional Assumptions | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.0 Cable Plant Characteristics | This clause describes the characteristics of a cable television plant, assumed to be for the purpose of operating a data- over-cable system. The cable plants have very diverse physical topologies. These topologies range from fiber to the home node architectures as well as fiber nodes with many actives in cascade. The p... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.1 Overview | The present document defines the PHY layer protocol of DOCSIS 3.1. It also describes the channel assumptions over which DOCSIS 3.1 systems are expected to operate. DOCSIS 3.1 ultimate service goal of multi-gigabit per second in the downstream direction and gigabit per second in the upstream direction resulted in signif... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2 Functional Assumptions | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.1 Equipment Assumptions | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.1.1 Frequency Plan | In the downstream direction, the cable system is assumed to have a pass band with a lower edge of either 54 MHz, 87,5 MHz, 108 MHz or 258 MHz, and an upper edge that is implementation-dependent but is typically in the range of 550 to 1 002 MHz. Upper frequency edges extending to 1 218 MHz, 1 794 MHz and others are expe... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.1.2 Compatibility with Other Services | The CM shall coexist with any services on the cable network. The CMTS shall coexist with any services on the cable network. In particular: • The CMTS shall be interoperable in the cable spectrum assigned for CMTS and CM interoperation while the balance of the cable spectrum is occupied by any combination of television ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.1.3 Fault Isolation Impact on Other Users | As CMTS transmissions are on a shared-media, point-to-multipoint system, fault-isolation procedures should take into account the potential harmful impact of faults and fault-isolation procedures on numerous users of the data-over-cable, video and other services. For the interpretation of harmful impact, see clause 5.2.... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.1.4 Cable System Terminal Devices | The CM is expected to meet and preferably exceed all applicable regulations for Cable System Termination Devices and Cable Ready Consumer Equipment as defined in FCC Part 15 [14] and Part 76 [15]. None of these specific requirements may be used to relax any of the specifications contained elsewhere within the present d... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.2 RF Channel Assumptions | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.2.0 Cable Networks Interoperability | The data-over-cable system, configured with at least one set of defined physical-layer parameters (e.g. modulation, interleaver depth, etc.) from the range of configurable settings described in the present document, is expected to be interoperable on cable networks having characteristics defined in this clause. This is... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.2.1 Transmission Downstream | The RF channel transmission characteristics of the cable network in the downstream direction are described in table 5.1. These numbers assume total average power of a digital signal in a 192 MHz channel bandwidth for subcarrier levels unless indicated otherwise. For impairment levels, the numbers in table 5.1 assume av... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.2.2 Transmission Upstream | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.2.2.0 RF Channel Transmission Characteristics | The RF channel transmission characteristics of the cable network in the upstream direction are described in table 5.2. No combination of the following parameters will exceed any stated interface limit defined elsewhere in the present document. Transmission is from the CM output at the customer location to the headend. ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.2.2.1 Availability | Cable network availability is typically greater than 99,9 %. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.3 Transmission Levels | The nominal power level of the upstream CM signal(s) will be as low as possible to achieve the required margin above noise and interference. Uniform power loading per unit bandwidth is commonly followed in setting upstream signal levels, with specific levels established by the cable network operator to achieve the requ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 5.2.4 Frequency Inversion | There will be no frequency inversion in the transmission path in either the downstream or the upstream directions, i.e. a positive change in frequency at the input to the cable network will result in a positive change in frequency at the output. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6 PHY Sublayer for SC-QAM | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.1 Scope | This clause applies to cases where a DOCSIS 3.1 CM or CMTS is operating with SC-QAM operation only, with no OFDM/OFDMA operation and for the SC-QAM channels with simultaneous operation of SC-QAM and OFDM/OFDMA channels unless otherwise noted. As such, it represents backward compatibility requirements when operating wit... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2 Upstream Transmit and Receive | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.1 Overview | See clause 6.2.1 of [5], with the exceptions noted below. A CM shall support at least eight (8) active upstream channels (which are referred to as the Transmit Channel Set for that CM). A CMTS shall support at least eight (8) active upstream channels. A CMTS may support S-CDMA mode. If a CMTS implements S-CDMA mode, th... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.2 Signal Processing Requirements | See clause 6.2.2 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.3 Modulation Formats | See clause 6.2.3 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.4 R-S Encode | See clause 6.2.4 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.5 Upstream R-S Frame Structure (Multiple Transmit Enabled) | See clause 6.2.5 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.6 Upstream R-S Frame Structure (Multiple Transmit Disabled) | See clause 6.2.6 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.7 TDMA Byte Interleaver | See clause 6.2.7 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.8 Scrambler (Randomizer) | See clause 6.2.8 of [5]. ETSI ETSI TS 103 311-2 V1.1.1 (2017-02) 37 |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.9 TCM Encoder | See clause 6.2.9 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.10 Preamble Prepend | See clause 6.2.10 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.11 Modulation Rates | See clause 6.2.11 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.12 S-CDMA Framer and Interleaver | See clause 6.2.12 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.13 S-CDMA Framer | See clause 6.2.13 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.14 Symbol Mapping | See clause 6.2.14 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.15 S-CDMA Spreader | See clause 6.2.15 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.16 Transmit Pre-Equalizer | See clause 6.2.16 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.17 Spectral Shaping | See clause 6.2.17 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.18 Relative Processing Delays | See clause 6.2.18 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.19 Transmit Power Requirements | Applies only to cases where a DOCSIS 3.1 CM is operating with a DOCSIS 3.0 CMTS or where a DOCSIS 3.1 CMTS is operating with a DOCSIS 3.0 CM. See clause 6.2.19 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.20 Burst Profiles | See clause 6.2.20 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.21 Burst Timing Convention | See clause 6.2.21 of [5]. ETSI ETSI TS 103 311-2 V1.1.1 (2017-02) 38 |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.22 Fidelity Requirements | Applies only to cases where a DOCSIS 3.1 CM is operating with a DOCSIS 3.0 CMTS or where a DOCSIS 3.1 CMTS is operating with a DOCSIS 3.0 CM. See clause 6.2.22 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.23 Upstream Demodulator Input Power Characteristics | See clause 6.2.23 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.24 Upstream Electrical Output from the CM | Applies only to cases where a DOCSIS 3.1 CM is operating with a DOCSIS 3.0 CMTS or where a DOCSIS 3.1 CMTS is operating with a DOCSIS 3.0 CM. See clause 6.2.24 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.2.25 Upstream CM Transmitter Capabilities | Applies only to cases where a DOCSIS 3.1 CM is operating with a DOCSIS 3.0 CMTS or where a DOCSIS 3.1 CMTS is operating with a DOCSIS 3.0 CM. See clause 6.2.25 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.3 Downstream Transmit | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.3.1 Downstream Protocol | See clause 6.3.1 of [3]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.3.2 Spectrum Format | See clause 6.3.2 of [3]. 6.3.3 Scaleable Interleaving to Support Video and High-Speed Data Services See clause 6.3.3 of [3]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.3.4 Downstream Frequency Plan | See clause 6.3.4 of [3]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.3.5 DRFI Output Electrical | Applies only the case where a DOCSIS 3.1 device is operating in DOCSIS 3.0 mode only. For legacy, SC-QAMs, the EQAM and CMTS shall support the electrical output requirements specified in the following clauses and tables of [3]: • clause 6.3.5, DRFI Output Electrical; • clause 6.3.5.1, CMTS or EQAM Output Electrical; • ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.3.6 CMTS or EQAM Clock Generation | Applies only the case where a DOCSIS 3.1 CMTS is operating in a DOCSIS 3.0 mode only. See clause 6.3.6 of [3]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.3.7 Downstream Symbol Clock Jitter for Synchronous Operation | Applies only the case where a DOCSIS 3.1 CMTS is operating in a DOCSIS 3.0 mode only. See clause 6.3.7 of [3]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.3.8 Downstream Symbol Clock Drift for Synchronous Operation | Applies only the case where a DOCSIS 3.1 CMTS is operating in a DOCSIS 3.0 mode only. See clause 6.3.8 of [3]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.3.9 Timestamp Jitter | See clause 6.3.9 of [3]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.4 Downstream Receive | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.4.1 Downstream Protocol and Interleaving Support | See clause 6.3.1 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.4.2 Downstream Electrical Input to the CM | See clause 6.3.2 of [5], with the exceptions noted below. A CM shall support at least 24 active downstream channels. A CMTS shall support at least 24 active downstream channels. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.4.3 CM BER Performance | See clause 6.3.3 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.4.4 Downstream Multiple Receiver Capabilities | See clause 6.3.4 of [5]. ETSI ETSI TS 103 311-2 V1.1.1 (2017-02) 40 |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 6.4.5 Non-Synchronous DS Channel Support | Applies only to the case where a DOCSIS 3.1 CM operating with a DOCSIS 3.0 CMTS. See clause 6.3.5 of [5]. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7 PHY Sublayer for OFDM | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.1 Scope | The present document defines the electrical characteristics and signal processing operations for a cable modem (CM) and Cable Modem Termination System (CMTS). It is the intent of the present document to define an interoperable CM and CMTS such that any implementation of a CM can work with any CMTS. It is not the intent... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2 Upstream and Downstream Frequency Plan | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.0 System Spectrum Requirement | The following spectrum definitions are based on the system requirement that the downstream transmission frequencies always reside above the upstream transmission frequencies in the cable plant. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.1 Downstream CM Spectrum | The CM shall support a minimum of two independently configurable OFDM channels each occupying a spectrum of up to 192 MHz in the downstream. The CM shall support a downstream upper band edge of 1,218 GHz. The CM may support a downstream upper band edge of 1,794 GHz. The CM shall support a downstream lower band edge of ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.2 Downstream CMTS Spectrum | The CMTS shall support a minimum of two independently configurable OFDM channels each occupying a spectrum of up to 192 MHz in the downstream. The CMTS shall support a downstream upper band edge of 1,218 GHz. The CMTS may support a downstream upper band edge of 1,794 GHz. The CMTS shall support a downstream lower band ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.3 Upstream CM Spectrum | The CM shall support a minimum of two independently configurable OFDMA channels each occupying a spectrum of up to 96 MHz in the upstream. The CM may support more than two independently configurable OFDMA channels each occupying a spectrum of up to 96 MHz in the upstream. ETSI ETSI TS 103 311-2 V1.1.1 (2017-02) 41 The ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.4 Upstream CMTS Spectrum | The CMTS shall support a minimum of two independently configurable OFDMA channels each occupying a spectrum of up to 96 MHz in the upstream. The CMTS may support more than two independently configurable OFDMA channels each occupying a spectrum of up to 96 MHz in the upstream. The CMTS shall support upstream transmissio... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.5 Channel Band Rules | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.5.0 OFDM/OFDMA Channel Planning | During OFDM/OFDMA channel planning, the following rules are to be observed to ensure proper operation of DOCSIS 3.1 CMTS and CM. The CMTS shall ensure that the configured OFDM/OFDMA channels are aligned with the rules specified in clauses 7.2.5.2 and 7.2.5.3. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.5.1 Downstream Channel Bandwidth Rules | The CMTS shall ensure that the encompassed spectrum of a 192 MHz downstream OFDM channel does not exceed 190 MHz. Therefore the CMTS shall ensure that the number of contiguous active subcarriers in a downstream OFDM channel does not exceed 3 800 for 4K FFT and 7 600 for 8K FFT. When configured for 4K FFT, the CMTS shal... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.5.2 Downstream Exclusion Band Rules | The CM and CMTS are not expected to meet performance and fidelity requirements when the system configuration does not comply with the downstream exclusion band rules listed below. These rules apply to each OFDM channel and also to the composite downstream inclusive of OFDM and non-OFDM channels: • There has to be at le... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.5.3 Upstream Channel Bandwidth Rules | The CMTS shall ensure that the encompassed spectrum of a 96 MHz upstream OFDMA channel does not exceed 95 MHz. Therefore the number of contiguous active subcarriers in an upstream OFDMA channel shall not exceed 1 900 for 2K FFT and 3 800 for 4K FFT. When configured for 2K FFT, the CMTS shall only use subcarriers in the... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.2.5.4 Upstream Exclusion Band Rules | These rules apply to the upstream exclusion band: • Excluded subcarriers will only occur between minislots. • Subcarrier exclusions between minislots can be any integer number of subcarriers. There is no minimum subcarrier exclusion restriction. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.3 OFDM Numerology | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.3.1 Downstream OFDM Numerology | DOCSIS 3.1 uses OFDM for downstream modulation. Two modes of operation are defined for the downstream: 4K FFT and 8K FFT modes for a sampling rate of 204,8 MHz. These are described in clause 7.5.7. Table 7.1 summarizes the numerical values for the downstream OFDM parameters; a more detailed description of the parameter... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.3.2 Upstream OFDMA Numerology | DOCSIS 3.1 uses OFDMA (orthogonal frequency-division multiple access) for upstream modulation. OFDMA is a multi-user version of OFDM, and assigns subsets of subcarriers to individual CMs. The upstream OFDMA parameters are derived from the downstream parameters, and are summarized in table 7.2. A more detailed descripti... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.3.3 Subcarrier Clocking | The "locking" of subcarrier "clock and carrier" are defined and characterized by the following rules: • Each OFDM symbol is defined with an FFT duration (equal to subcarrier clock period) of nominally 20 µs or 40 µs. For each OFDM symbol, the subcarrier clock period (µs) may vary from nominal with limits defined in cla... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4 Upstream Transmit and Receive | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.1 Overview | This clause specifies the upstream transmission electrical and signal processing requirements for the transmission of OFDM modulated RF signals from the CM to the CMTS. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.2 Signal Processing Requirements | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.2.0 OFDMA Frames | Upstream transmission uses OFDMA frames. Each OFDMA frame is comprised of a configurable number of OFDM symbols, K. Several transmitters may share the same OFDMA frame by transmitting data and pilots on allocated sub-carriers of the OFDMA frame. There are several pilot patterns as described in clause 7.4.17. The struct... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.2.1 Framing | Figure 7.3 describes how the received bits from the PHY-MAC Convergence layers are framed before being converted into constellation symbols. The number of FEC codewords, corresponding codeword lengths and zero-padding bits are calculated by the PHY-MAC Convergence layer as described in clause 7.4.4.1 according to the a... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.2.2 Forward Error Correction Encoding | Data received from the PHY-MAC Convergence layer interface, along with the FEC padding, is LDPC encoded. The upstream has three LDPC codes: a long, medium, and short FEC code, as described in clause 7.4.4. Prior to encoding, the transmitter is to decide on the configuration of the codewords as described in clause 7.4.4... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.2.3 Randomizer and Symbol Mapper | The encoded bits are then randomized (scrambled) using the PRBS scrambler as specified in clause 7.4.5. The scrambler output bits are converted into constellation symbols according to the corresponding modulation order of the minislot. All subcarriers of a given type (Pilots, Complementary Pilots, Data subcarriers) in ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.2.4 OFDMA framer and Interleaver | Constellation symbols then enter the OFDMA framer and Interleaver block. The OFDMA framer adds pilots according to the pilot pattern associated with the transmission burst minislot. The constellation symbols are written to subcarriers associated with the transmission burst minislots and are then interleaved in time and... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.2.5 Pre-Equalization | The upstream transmitter applies pre-equalization as described in clause 7.4.18 in order to pre-distort the transmitted signals according to coefficients received from the CMTS to compensate for the channel response. |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.2.6 IFFT Transformation | In this stage each pre-equalized symbol is transformed into the time domain using the IFFT block. IFFT inputs that are not used (that is, that do not correspond to any of the minislots used by the transmission burst) are set to zero. The transmitter converts the output of the IFFT from parallel to serial and performs c... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.2.7 Cyclic Prefix and Windowing | A segment at the end of the IFFT output is prepended to the IFFT output; this is referred to as the Cyclic Prefix (CP) of the OFDM symbol. For windowing purposes, another segment at the start of the IFFT output is appended to the end of the IFFT output - the roll-off period (RP). The addition of a cyclic prefix enables... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.3 Time and Frequency Synchronization | |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.3.0 Timing and Frequency Synchronization Requirements | CM upstream frequency and timing of transmissions is based on downstream tracking, and in the case of timing, also based upon receiving and implementing timing adjustments from the CMTS. This clause describes the CM upstream transmission performance requirements on frequency and timing which are based upon tracking the... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.3.1 Channel Frequency Accuracy | To support OFDMA upstream using legacy downstream, the CM shall provide upstream frequency accuracy, relative to the downstream reference, of ≤ ±20 Hz in at least Five Sigma of upstream grants, under all the downstream conditions detailed in clause 7.5.9. Upstream frequency accuracy measurements are averaged over the d... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.3.2 Channel Timing Accuracy | For OFDMA upstream, regardless of what is used for the timing master, the ranging time offset will be given as described in [4]. Specifically, this timestamp has an integer portion of 10,24 MHz clocks. It also has an integer portion of counting 1/20ths duration of 10,24 MHz clock period (this integer portion counts up ... |
6bff1d8e6adfce5063e1e51e244276b5 | 103 311-2 | 7.4.3.3 Modulation Timing Jitter | The CM shall implement the upstream timing so that the OFDMA clock timing error (with the mean error subtracted out) relative to the CMTS master clock as measured at the CMTS will be within ±10 ns in each burst measured within 35 s measurement duration. This applies to the worst-case jitter and frequency drift specifie... |
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